81ADANSONIA, sér. 3 • 2011 • 33 (1) © Publications Scientifi ques du Muséum national d’Histoire naturelle, Paris. www.adansonia.com

Hughes M. 2011. — A new species of fl eshy-fruited Begonia (Begoniaceae) from the Masoala Peninsula, Madagascar. Adansonia, sér. 3, 33 (1) : 81-85. DOI: 10.5252/a2011n1a4.

ABSTRACTA new species of Begonia (B. masoalaensis M.Hughes, sp. nov.) is described from the Masoala Peninsula in north-east Madagascar. Th e species has fl eshy fruit, but bears no other similarity to other fl eshy fruited Begonia from Madagascar, and hence probably represents a secondary acquisition of this character, pos-sibly to facilitate zoochory. Begonia masoalaensis possesses an unusual spicate infl orescence architecture, derived from a highly modifi ed monochasial cyme. It is considered to be in the “Vulnerable” IUCN Red List category (VUD2).

RÉSUMÉUne nouvelle espèce de Begonia à fruits charnus (Begoniaceae) de la péninsule de Masoala, Madagascar.Une nouvelle espèce de Begonia (B. masoalaensis M.Hughes, sp. nov.) de la péninsule de Masoala au nord-est de Madagascar est décrite. Cette espèce pos-sède des fruits charnus, mais ne présente pas d’autre caractère commun avec les autres Begonia à fruits charnus de Madagascar, et montre donc probable-ment une acquisition secondaire de ce caractère, qui facilite potentiellement la zoochorie. Begonia masoalaensis possède une architecture d’infl orescence en épi inhabituelle, dérivée d’une cyme monochasiale hautement modifi ée. Cette espèce est considérée comme appartenant à la catégorie “Vulnérable” de la Liste Rouge de l’UICN (VUD2).

MOTS CLÉSBegoniaceae,

Begonia,Madagascar,fruit charnu,

espèce nouvelle.

KEY WORDSBegoniaceae,

Begonia,Madagascar,fl eshy fruit,

new species.

Mark HUGHESRoyal Botanic Garden Edinburgh,

20a Inverleith Row, Edinburgh, EH3 5LR (United Kingdom)m.hughes@rbge.ac.uk

A new species of fl eshy-fruited Begonia (Begoniaceae) from the Masoala Peninsula, Madagascar

82 ADANSONIA, sér. 3 • 2011 • 33 (1)

Hughes M.

INTRODUCTION

Th e large genus Begonia is currently represented on Madagascar by 48 species (Keraudren-Aymonin 1983) which belong to fi ve sections (Begonia sec-tions Erminea, Mezierea, Muscibegonia, Nervipla-centaria and Quadrilobaria). With one exception (Begonia oxyloba Welw. ex Hook.f. from Begonia sect. Mezierea), these species are endemic to Mada-gascar and surrounding islands (the Comoros, Réunion and Mauritius) and are the result of a monophyletic radiation, with origins in the mid Miocene c. 11 million years ago (Plana et al. 2004). Th e vast majority of these endemic species have papery, three-winged dehiscent fruits, but three of them (B. salaziensis Warb., B. humbertii Ker-audren and B. comorensis Warb.) have cylindrical, indehiscent fruits with fl eshy walls. In this respect, they resemble the only non-endemic species found in Madagascar, B. oxyloba Warb., and are placed with it in Begonia sect. Mezierea, for which fl eshy fruits are a diagnostic character. Th e new species described here, B. masoalaensis M.Hughes, sp. nov. (Fig. 1), also has a wingless fruit with fl eshy walls, but diff ers signifi cantly from members of Begonia sect. Mezierea in having a tuberous habit and axile (not parietal) placentation within the fruit. Th ese characters would place this new taxon nearer to the other endemic Malagasy sections listed above, and it therefore probably represents a case of secondary acquisition of fruit characters, which are suited for animal dispersal. A similar scenario of multiple origins for fl eshy fruit has been described in Asian Begonia (Tebbitt et al. 2006). It is diffi cult to as-sign this new species to any of the existing sections known from Madagascar (Doorenbos et al. 1998), given its unusual fruit morphology. Furthermore, the infl orescence structure is also very unusual. Although not perfectly known, it appears to be a spike, derived from a highly modifi ed monocha-sial cyme. Despite the excellent monograph of Malagasy Begonia published in 1983 (Keraudren-Aymonin 1983), this new species highlights that there are still striking discoveries to be made on Madagascar, and hence I hesitate to create a new section to accommodate it until further mono-graphic and phylogenetic work is carried out.

Begonia masoalaensis is endemic to the Masoala Peninsula in the north-east of Madagascar (Fig. 2). Th e other three species currently known from the Masoala region (Begonia lyallii A.DC., B. tsimihety Humbert and B. antongilensis Humbert) diff er in having winged fruit.

SYSTEMATICS

Begonia masoalaensis M.Hughes, sp. nov. (Fig. 1)

Begonia masoalaensis sp. nov. tuberis praesentia et foliis maculatis marginibus sinuosis a ceteris speciebus madagascariensibus et insulis affi nibus cum fructu carnoso (B. comorensis, B. humbertii, B. oxyloba et B. salaziensis) diff ert.

TYPUS. — Madagascar. Antsiranana, Masoala Peninsula, forest surrounding research station at Anronabe on west coast, 15°39’30”S, 49°57’30”E, 0-600 m, 19.II.1992, Zjhra & Hutcheon 175 (holo-, MO; iso-, E).

DESCRIPTION

Tuberous repent herb to 10-20 cm high. Tuber c. 2 × 0.8 cm when dry, elliptic, narrowing at the ends, circular in cross section. Stem to c. 8 cm long, with many adventitious roots, hairy, more so towards the apex, hairs simple, c. 1.5 mm long. Stipules persistent, c. 6 mm long with hairs on the keel. Leaves 2-3 in number; petiole 1-5 cm long, densely covered in 1.5 mm long simple hairs; lamina green with an even covering of tiny white or red dots, 8-22 × 5-11 cm in total, 7-16 cm long from point of petiole attachment to tip, ovate, markedly asymmetric, cordate at base, venation palmate-pinnate; margin sinuate, denticulate with a fringe of hairs c. 0.25 mm long. Infl orescence terminal, spicate, bisexual, usually with two main axes, each terminating in a female fl ower, primary peduncle c. 3 cm long; bracts persistent, 2-3 mm long, glabrous; male fl owers with 4 white tepals, outer sub orbicular, c. 5 mm in diameter, inner linear-elliptic to c. 5 mm long; stamens c. 15, fi laments 1.5 mm long, free, anthers just over 1 mm long, elliptic-oblong, not hooded, dehiscing through slits running the entire length of the anther; female fl owers with 4 white tepals, similar in shape and

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A new Malagasy Begonia (Begoniaceae)

ADANSONIA, sér. 3 • 2011 • 33 (1)

dimensions to those in the male fl owers, ovary cigar-shaped, c. 1 cm long on fl owering, stigmas 3, stigmatic surface in a simple U-shaped band. Fruit fl eshy, cigar-shaped, c. 3 cm long, 3 mm wide

when dried, glabrous, indehiscent; placentation axile, placentae bifi d. Seeds barrel-shaped, size at maturity not known, collar cells less than ⅓ the length of the seed.

FIG. 1. — A, Begonia masoalaensis M. Hughes, sp. nov., bearing two female fl owers with the scars of the shed male portion of the infl orescence below: B, cross section of ovary; C, male fl ower. Scale bars: A, C, 1 cm; B, 5 mm.

B

A C

A, C

84 ADANSONIA, sér. 3 • 2011 • 33 (1)

Hughes M.

DIAGNOSTIC CHARACTERS

Begonia masoalaensis diff ers from other Malagasy and neighbouring islands species with fl eshy fruit (B. comorensis, B. humbertii, B. oxyloba and B. sala-ziensis) in having a tuber and spotted leaves with sinuate edges.

CONSERVATION ASSESSMENT

Th e Masoala National park is currently well pro-tected (C. Kremen pers. com.). However, this spe-cies is currently known only from the type locality, which is at a low altitude just within the border of the reserve, and hence is considered to be Vulner-

able (VUD2) (Standards and Petitions Working Group 2006).

AcknowledgementsTh e author thanks the curators of E, MO & P for allowing access to specimens, Robert Mill for the translating the diagnosis into Latin, and two review-ers for helpful comments. Th e support of the M.L. MacIntyre Begonia Trust, Th e Sibbald Trust and SYNTHESYS (grant FR-TAF 1416) is gratefully acknowledged. Th is research was carried out at the Royal Botanic Garden Edinburgh, supported by

FIG. 2. — Map of the Masoala Peninsula in Madagascar, showing the National park and the location of Begonia masoalensis M. Hughes, sp. nov. ( ). Vegetation data derived from Du Puy & Moat (1997).

Modified habitat

N

Coastal forest

Evergreen humid forest (low alt.)Evergreen humid forest (mid alt.)

Vegetation type:National park

20 km

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the Rural and Environment Research and Analysis Directorate of the Scottish Government.

REFERENCES

DOORENBOS J., SOSEF M. S. M. & DE WILDE J. J. F. E. 1998. — Th e sections of Begonia, including descrip-tions, key and species lists (Studies in Begoniaceae VI). Wageningen Agricultural University Papers 98 (2): 1-266.

DU PUY D. J. & MOAT J. 1997. — Madagascar Remaining Primary Vegetation Classifi ed by the Underlying Geology. Royal Botanic Gardens, Kew, UK, http://www.kew.org/gis/projects/madagascar/download.html.

KERAUDREN-AYMONIN M. 1983. — Bégoniacées, in LEROY J.-F. (ed.), Flore de Madagascar et des Comores,

fam. 144. Muséum national d’Histoire naturelle, Paris: 7-108.

TEBBITT M. C., FORREST L. L., SANTORIELLO A., CLEM-ENT W. L. & SWENSEN S. M. 2006. — Phylogenetic relationships of Asian Begonia, with an emphasis on the evolution of rain-ballist and animal dispersal mechanisms in sections Platycentrum, Sphenanthera and Leprosae. Systematic Botany 31 (2): 327-336.

PLANA V., GASCOIGNE A., FORREST L. L., HARRIS D. & PENNINGTON R. T. 2004. — Pleistocene and pre-Pleistocene Begonia speciation in Africa. Molecular Phylogenetics and Evolution 31 (2): 449-461.

STANDARDS AND PETITIONS WORKING GROUP 2006. — Guidelines for Using the IUCN Red List Categories and Criteria. Version 6.1. Prepared by the Standards and Petitions Working Group of the IUCN SSC Biodi-versity Assessments Sub-Committee, 60 p.

Submitted on 30 September 2010;accepted on 29 January 2011.